package dxp;
import java.math.BigInteger;

public class BitString
{
	public BitString(String s1,String s2,int len)
	{
		this.s1 = s1;
		this.s2 = s2;
		this.len = len;
	}
	private String s1;
	private String s2; 
	private int len;
	
	public String xor()
	{
		StringBuffer sb = new StringBuffer(); 
		for(int i = 0; i < len;++i)
		{
			sb.append(s1.charAt(i)==s2.charAt(i)?'0':'1');
		}
		return sb.toString();
	}
}
